Abstract: In the context of digital society, digital literacy has become an increasingly critical factor contributing to health inequality. As smart fitness gains widespread popularity, it has emerged as a key pathway through which digital literacy influences individual health outcomes. This study explores how digital literacy and smart fitness affect physical and mental health, and uncovers the mechanisms behind these effects. Drawing on data from a national online survey, regression analysis, mediation analysis and coefficient clustering analysis were employ to test the theoretical hypotheses above. The results reveal that: ① higher levels of digital literacy are significantly associated with better physical and mental health among internet users; ② smart fitness positively contributes to both physical and mental well-being; ③ digital literacy enhances health by promoting participation in smart fitness; and ④ the health-promoting effects of digital literacy and smart fitness are more pronounced than those of socioeconomic status. To advance the Healthy China initiative, it is essential to enhance the digital literacy of the general population and foster an inclusive digital society. Strategic efforts should focus on the development of smart fitness by accelerating technological innovation, improving infrastructure, integrating resources, and encouraging multi-stakeholder collaboration. Moreover, improving the usability and accessibility of smart fitness products and services is crucial to lowering technical barriers and delivering equitable public health services for all.